Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$87.86	10.379%	$96.979	$96.98	$97.00	$97.00
Purchase #2	$89.67	10.864%	$99.4117	$99.41	$99.40	$99.40
Purchase #3	$124.74	4.796%	$130.7225	$130.72	$130.70	$130.70
Purchase #4	$127.63	7.648%	$137.3911	$137.39	$137.40	$137.40
Purchase #5	$64.95	10.794%	$71.9607	$71.96	$71.95	$72.00
Purchase #6	$62.59	3.862%	$65.0072	$65.01	$65.00	$65.00
Purchase #7	$143.73	5.459%	$151.5762	$151.58	$151.60	$151.60
7 purchase totals =	$701.17		$753.0484	$753.05	$753.05	$753.10